With the popularity of portable consumer electronic products, such as smart phones, tablet computers, and so forth, stacked-die assemblies become more and more attractive in microelectronics packages to achieve electronics densification in a small footprint. However, the thickness of each stacked semiconductor die may result in a large thickness of the microelectronics package, which may not meet low-profile requirements for modern portable products. Such low profile requirements limit significantly the number of the semiconductor dies that can be stacked.
In the microelectronics package, the stacked semiconductor dies may convey signals to each other by different coupling methods, such as magnetic coupling and capacitive coupling. The magnetic coupling may be used to transfer signals between non-electrical-connection stacked dies. However, the signal transfer function is critically dependent on the precise value of magnetic coupling coefficients, and such precision in the magnetic coupling coefficients imposes strict constraints on the alignment between stacked semiconductor dies. Accurate alignment techniques, such as optical alignment, are very expensive and not preferred for low cost products. Consequently, the capacitive coupling, which has well defined capacitive coupling coefficients and does not suffer significantly from shifts and misalignments in a stacked-die assembly process, is widely utilized to transfer signals between stacked dies. The key requirement for the capacitive coupling is to have electric connections between the stacked semiconductor dies.
Accordingly, there remains a need for improved microelectronics package designs, which accommodate the low-profile requirements for portable products and avoid superior alignment request in semiconductor die stacking assembly without expensive and complicated processes.